If the parser cannot not find a word in the current vocabulary search path, it attempts to look for the word in all loaded vocabularies.
mode is off, a restartable error is thrown with a restart for each vocabulary in question, together with a restart which defers the word in the current vocabulary, as if DEFER:
mode is on and only one vocabulary has a word with this name, the vocabulary is added to the search path and parsing continues.
If any restarts were invoked, or if auto-use?
is on, the parser will print the correct USING:
after parsing completes. This form can be copy and pasted back into the source file.